1. Field of the Invention
The present invention relates generally to devices and instrumentation for intervertebral disc diagnosis and treatment, and methods thereof.
2. Description of the Related Art
An intervertebral disc performs the important role of absorbing mechanical loads while allowing for constrained flexibility of the spine. The disc is composed of a soft, central nucleus pulposus surrounded by a tough, woven anulus fibrosis. Herniation is a result of a weakening in the anulus. Symptomatic herniations occur when weakness in the anulus allows the nucleus to bulge or leak posteriorly toward the spinal cord and major nerve roots. The most common symptoms of herniation include pain radiating along a compressed nerve and lower back pain, both of which can be crippling for the patient. Herniation, and the resulting dehabilitating symptoms, are of significant medical concern in the United States because of the low average age of diagnosis. Indeed, over 80% of patients in the United States diagnosed with herniation are under the age of 59.
Information regarding anular thickness, internal dimensions of the disc space normally occupied by the nucleus, and the location of anular apertures and lesions in relation to the vertebral endplates and lateral walls of the anulus facilitates accurate diagnosis and treatment of intervertebral disc conditions. For example, medical procedures involving the implantation of an artificial nucleus or anular augmentation depend on this information for accurate sizing of such implants. Also important are safe, dependable, and minimally invasive methods and devices for the manipulation of anular and nuclear tissue, especially along the inner wall of the posterior anulus. For example, tissues in the anulus and nucleus are commonly removed or manipulated during the implantation of artificial discs either to clear a path for the insertion of other types of prosthetic devices or as part of a discectomy procedure.
Specialized tools have evolved for the surgical treatment of intervertebral discs in the lumbar, cervical, and thoracic spine, which have suffered from tears in the anulus fibrosis or herniation of the nucleus pulposus. These tools are well-known in the prior art. The devices of the prior art, however, are designed for specific procedures, including complete discectomies (as opposed to partial discectomy or minute removal of tissue) and the installation of vertebral fusion implants. Accordingly, these devices cannot be used to manipulate anular and nuclear tissue in a precise and minimally invasive manner. Moreover, such devices are typically designed to access the disc using an anterior approach, i.e., through the abdomen. Although an anterior surgical approach provides direct access to intervertebral discs, it is highly invasive to the abdominal organs. Thus, surgery is typically more complicated and time consuming. A direct posterior approach is not anatomically practicable because the spinal cord and its surrounding bony protective sheath lies directly in front of each vertebral disc. An posterior-lateral aspect approach is the least invasive of these methods but provides limited and oblique access to the disc and its interior. Depending upon the surgical necessities involved, several methods of percutaneous disc tissue manipulation are available, including chemonucleolysis (e.g., U.S. Pat. No. 4,439,423), laser (e.g., U.S. Pat. No. 5,437,661), manual, focused energy, ultrasonic disruption (e.g., U.S. Pat. No. 5,772,661), arthroscopy and endoscopy.
Endoscopic instrumentation has evolved over the past 25 years and permits viewing, irrigation, suction, and cutting. Probes that permit automated percutaneous suction such as nucleotomes or cylindrically housed rotating cutting means, such as debreders, provide gross but efficient removal of disc tissue. Varying tip profiles control the amount and direction of tissue resection as well as the likelihood of damage to surrounding tissue. These devices tend to be limited by the size of the cannula which houses the instrumentation and its ability to maneuver around vertebral bodies and delicate tissues of the spine.
Hand tools for use in the spine are also well known and can be inserted through cannulae or freely guided by hand. These tips may be blades, burs, rongeurs, curettes or forcep-like xe2x80x9cgraspersxe2x80x9d that are capable of pinching of small amounts of material. To the extent that these instruments can access the various tissues, these devices provide good tactical feedback and control. However, if used in an antero-lateral spinal approach, these tools are generally limited by the indirect approach necessitated by the laminae and spinous processes of the adjacent vertebrae, and thus, access to tissues is substantially hampered.
Some intervertebral disc devices have been designed with flexible tips that are designed not to perforate or deflect off of the interior surface of the disc. Unfortunately, such tips deflect off of healthy disc tissue only, not the pathological tissue that caused the need for the surgery in the first place. Thus, such instrumentation can exit the anulus and cause considerable damage to the surrounding tissues and spinal cord. Also, the flexible probe tips on some instruments which permit access to remote locations within the disc can only do so by sacrificing direct control because the devices are passively guided or blindly xe2x80x9csnakedxe2x80x9d within the disc. Accordingly, delicate and precise work within a disc is not possible with such instruments.
Among other disadvantages, the devices and methods of the prior art are typically invasive and destructive to surrounding tissue, frequently causing disc infection and nerve root injury. Moreover, such devices are unable to precisely manipulate disc material along the posterior anulus in a minimally invasive manner. Accordingly, there is a need for an intervertebral disc diagnostic and manipulation device which is capable of performing delicate and precise work within a disc, especially along the posterior anulus and between anular lamella.
The current invention relates generally to devices and instrumentation for intervertebral disc diagnosis and treatment, and methods thereof. In several embodiments, the present invention provides for a minimally invasive and actively guided intervertebral disc repair and diagnostic device. This device provides direct and consistent access to the inner surface of the posterior anulus and will not unintentionally exit the posterior anulus and cause harm to the spinal cord. One skilled in the art will understand that this device is not limited to intervertebral disc applications, but includes medical procedures in which a minimally invasive, actively guided device for diagnosis, repair or treatment is desired. These procedures include, but are not limited to, arthroscopic, endoscopic, and endovascular applications. Further, one skilled in the art will appreciate that, in many embodiments, this invention may be used percutaneously or intralumenally.
Various embodiments of the invention may be guided by tactile feedback or through active viewing. Also, various embodiments may be used in conjunction with medical imaging technologies, including MRI, ultrasound, or fluoroscopy. Further, several embodiments of the invention having radiopacity or selective radiopacity may be used in conjunction with imaging methods for guidance and/or to facilitate measurement of organs or tissues.
Various embodiments of the current invention are particularly advantageous because they provide active controlled direction of the working end of the instrument within the anulus or nucleus. Further, several embodiments provide access to the posterior portion of the anulus using a posterior surgical approach. In various embodiments, access to the posterior anulus, via circumferential navigation of the instrument as it is deflected from the lateral, anterior, opposite lateral, and finally to the posterior anulus, is avoided. This is advantageous because circumferential deflection of the working end of the instrument within the anulus can result in the tip of the instrument passing through a fissure in the posterior anular surface and outward to the spinal cord. This can occur because the circumferential navigation from a typical posterior surgical approach eventually directs the tip perpendicular to the posterior anular surface, which may contain lesions large enough to allow protrusion of the tip directly through to the spinal cord.
There is provided in accordance with one aspect of the present invention, a device for treating the spine. The device comprises an elongate guide having a longitudinal axis. An axially moveable actuator is carried by the guide. A probe is movable with the actuator, and a deflection surface is carried by the guide. Axial movement of the actuator causes the probe to advance along the deflection surface and extend away from the guide at an angle to the longitudinal access of the guide.
In one implementation of the invention, the guide comprises an elongate tubular body having at least one lumen extending therethrough. The actuator extends through at least a portion of the guide. The probe may comprise an elongate flexible body, attached to the actuator. The probe may be biased in a nonlinear configuration. In one embodiment, the probe comprises a nickel titanium alloy.
In accordance with another aspect of the present invention, there is provided a method of treating a disc in the spine. The method comprises the steps of advancing a device at least part way through an anulus. A probe is advanced laterally from the device in a first direction along a portion of the anulus.
In one application of the invention, the advancing a probe step comprises advancing the probe in between adjacent (anular lamella) layers of the anulus. In another application of the invention, the advancing a probe step comprises advancing the probe along an interior surface of the anulus, between the anulus and the nucleus. The method may further comprise the step of repositioning the probe and advancing the probe in a second direction along a second portion of the anulus.
In accordance with a further aspect of the present invention, the method additionally comprises the step of introducing media through the delivery device and into the disc. In one application, the media comprises contrast media, to permit fluoroscopic visualization. The media may alternatively or additionally comprise a medication, and/or a nucleus augmentation material. The method may additionally comprise the step of introducing a prosthesis into the disc. The prosthesis may be introduced by proximately retracting a push rod from a lumen in the delivery device, and introducing the prosthesis into the disc through the lumen.
As will be appreciated by those of skill in the art, the present invention, therefore, provides a minimally invasive access pathway into the anulus and/or nucleus of a vertebral disc. The pathway may be utilized to perform any of a wide variety of procedures, including diagnostic and therapeutic procedures, some of which will be identified below.
Several embodiments of this invention provide a new intervertebral disc manipulation and diagnostic device.
One or more embodiments disclosed herein provide a convenient, reliable, and accurate way to measure the anular thickness and the internal dimensions of the disc space normally occupied by the nucleus pulposus.
Several embodiments of this invention provide a device useful in determining various disc dimensions in order to enable a surgeon to size various implants and tools and facilitate their guidance within the disc.
Various embodiments provide for the manipulation through an opening in the anulus. Manipulation includes, but is not limited to, dissection, resection or ablation of disc tissue. The opening may be a single iatrogenic hole, such as an anulotomy, a naturally occurring hole, or a lesion in the anulus.
One or more aspects of the current invention prepare or manipulate disc tissue in preparation for the insertion of an implant or other instruments.
Several embodiments of the present invention diagnose and manipulate disc tissue with minimal invasiveness and risk of unintended passage of the device outside of the posterior anulus in the direction of the spinal cord or other sensitive areas proximal thereto.
Various aspects of this invention permit direct access to the interior aspect of anulus via an anulotomy.
Several embodiments of invention provide an intervertebral disc manipulation and diagnostic device wherein the travel of the working end of the device is parallel to the lamellae of the anulus.
This disclosure utilizes particular orthopedic references, nomenclature, and conventions. Accordingly, several background figures and descriptions are included to aid in the understanding of the environment under which specific embodiments of the invention may be used. In this description and the following claims, the terms xe2x80x9canteriorxe2x80x9d and xe2x80x9cposteriorxe2x80x9d, xe2x80x9csuperiorxe2x80x9d and xe2x80x9cinferiorxe2x80x9d are defined by their standard usage in anatomy, i.e., anterior is a direction toward the front (ventral) side of the body or organ, posterior is a direction toward the back (dorsal) side of the body or organ; superior is upward (toward the head) and inferior is lower (toward the feet).